Blar i NTNU Open på forfatter "Ortega-Cerdà, Joaquim"

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    • Contractive inequalities for Bergman spaces and multiplicative Hankel forms 

      Bayart, Frédéric; Brevig, Ole Fredrik; Haimi, Antti; Ortega-Cerdà, Joaquim; Perfekt, Karl-Mikael (Journal article; Peer reviewed, 2019)
      We consider sharp inequalities for Bergman spaces of the unit disc, establishing analogues of the inequality in Carleman's proof of the isoperimetric inequality and of Weissler's inequality for dilations. By contractivity ...

    • Contractive inequalities for Hardy spaces 

      Brevig, Ole Fredrik; Ortega-Cerdà, Joaquim; Seip, Kristian; Zhao, Jing (Journal article; Peer reviewed, 2018)
      We state and discuss several interrelated results, conjectures, and questions regarding contractive inequalities for classical Hp spaces of the unit disc. We study both coefficient estimates in terms of weighted ℓ 2 sums ...

    • A converse to the Schwarz lemma for planar harmonic maps 

      Brevig, Ole Fredrik; Ortega-Cerdà, Joaquim; Seip, Kristian (Peer reviewed; Journal article, 2021)
      A sharp version of a recent inequality of Kovalev and Yang on the ratio of the (H1)∗ and H4 norms for certain polynomials is obtained. The inequality is applied to establish a sharp and tractable sufficient condition for ...

    • Hilbert points in Hardy spaces 

      Brevig, Ole Fredrik; Ortega-Cerdà, Joaquim; Seip, Kristian (Peer reviewed; Journal article, 2023)

    • Idempotent Fourier multipliers acting contractively on Hp spaces 

      Brevig, Ole Fredrik; Ortega-Cerdà, Joaquim; Seip, Kristian (Peer reviewed; Journal article, 2021)
      We describe the idempotent Fourier multipliers that act contractively on Hp spaces of the d-dimensional torus Td for d≥1 and 1≤p≤∞. When p is not an even integer, such multipliers are just restrictions of contractive ...